The invention relates to the field of force-transmission belts for belt drives. These can be flat belts, V-belts, V-ribbed belts or toothed belts. Belts for belt drives generally have to meet particular dynamic-mechanical requirements. During operation the belts experience slight internal heating due to interior shear forces, but in modern elastomer belts this heating is not problematic. Belts of the type concerned here are often used in high-performance machinery or in engines. Particularly in vehicle engines for land vehicles, watercraft, and aircraft they can be exposed to heat from exterior sources, resulting from a high operating temperature of the engine, and in the case of internal combustion engines also from high exhaust-gas temperatures. The belt material is subject to additional stress from these exterior conditions. There is the risk that the belt ages more rapidly, with a resultant reduction of operating lifetime. The belts in engine compartments of motor vehicles are exposed briefly and occasionally to high temperatures up to about 300 or 400° C. The resistance of elastomer belts to high temperatures is therefore a specific problem.
Force-transmission belts of this type are traditionally often produced from rubber elastomers, and specifically preferably those of the M type or of the R type, inclusive of natural rubber (NR). In the prior art these rubbers are often carbon-black-filled to provide a good price-performance ratio in relation to the desired mechanical properties.
It is already known that resistance to temperature change at high and/or low temperatures can be improved by using elastomers which have been optimized particularly for that purpose and which have better capability of withstanding said temperatures. EP 1 129 308 A2 discloses a force-transmission belt which withstands temperatures from −40 to about 140° C. for at least 500 hours. For this, specific copolymers are used which comprise nitrile groups and optionally fluorinated vinyl groups or unsaturated carboxylic ester groups. The use of specific synthetic elastomers for increasing resistance to temperature change has the attendant disadvantage that certain mechanical properties cannot be optimized at the same time as the resistance to temperature change. These specific synthetic elastomers are also often more expensive to produce.